Interpretive Summary: Soybean is a rich and inexpensive source of proteins for humans and animals. A substantial amount of information has been reported on the genotypic variation of soybeans. For better understanding of the consequences of genetic manipulation, elucidation of soybean protein composition and variation is necessary, because of its direct relationship to phenotype. However, knowledge of soybean genotypic variation alone does not provide adequate information concerning alteration of protein production due to environmental interactions. Therefore, we have conducted studies to determine and compare the composition of storage proteins between wild and cultivated genotypes using a combined proteomics approach. These results are relevant to understanding factors that impact both food quality and composition in soybean and related legumes. In addition, this investigation will be useful for scientists who wish to make genetic alteration of soybean for producing storage proteins with better quality and also helpful for consumer to have a greater understanding about the soy proteins available in the market.

Technical Abstract:
A combined proteomics approach was applied for the separation, identification, and comparison of two major storage proteins, '-conglycinin and glycinin in wild (Glycine soja) and cultivated (Glycine max) soybean seeds. Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) with three immobilized pH strips was an effective method to separate a large number of abundant and less-abundant storage proteins. Most of the subunits of '-conglycinin were well separated in the pH range 3.0-10.0, while acidic and basic glycinin polypeptides were well separated in pH range 4.0-7.0 and 6.0-11.0, respectively. Though the overall distribution pattern of the protein spots was similar in both genotypes using pH 3.0-10.0, number and intensity of the protein spots varied significantly when we used pH 4.0-7.0, and 6.0-11.0 ranges. The total number of storage protein spots detected in wild and cultivated genotypes was approximately 44 and 34, respectively. This is the first study reporting the comparison of protein profiles of wild and cultivated genotypes of soybean seeds using proteomics tools.